would the slicks work?

So my friend is thinking of buying my slicks. He has a 05 GT I have a 2002 GT.

Now the rims i know are same bolt pattern, but the rims are 15x8 with a 4.5in backspacing. I told him he might need a spacer if anything to fit. Am I correct? if he even does need a spacer what size? Help wuld be appreciated.